Prospective cancer epidemiology cohorts (CECs) can simultaneously investigate how genes, biomarkers, the environment, and lifestyle together affect cancer incidence, mortality, and clinical outcomes. The prospective California Teachers Study (CTS) began in 1995, when 133,479 female public school professionals completed a self-administered questionnaire. Participants have since completed three more questionnaires on lifestyle and environmental exposures. CTS data are regularly linked with California databases to identify essentially all incident cancers, hospitalizations, and deaths. CTS participants have donated 5,428 blood and 7,549 saliva samples in targeted projects to date. To enable broader etiologic, clinical, and translational research on genetic, molecular, and environmental predictors of cancer incidence, mortality, and outcomes, this project will collect pre diagnostic biospecimens from 27,625 CTS participants who have not previously donated a biospecimen. The specific aim is to collect, process, and store 1) a venous blood or saliva sample and 2) an overnight urine specimen from participants who are <70 years old and living in California. Coordinated teams of experienced field staff based at three CTS centers (City of Hope, Cancer Prevention Institute of California, and University of California, Irvine) will visit participants i person and collect, process, and store biospecimens using proven and standardized protocols. Adding this large group of pre diagnostic biospecimens to the extensive existing and future CTS risk-factor, cancer, hospitalization, and mortality data will directly facilitate numerous high-impact research projects in the CTS and in established large-scale consortia. This is an optimal time to collect new biospecimens because these participants will soon reach the age groups of peak cancer incidence. Combining the extensive exposure and lifestyle data collected in the CTS since 1995 with genetic, epigenetic, and other biomarkers in blood, urine, and saliva will directly facilitate future research on gene-environment interactions, natural history and progression, early detection, risk-prediction models, factors that affect response to treatment, and other emerging areas in cancer research.